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About

About

I have been working at INESCTEC since 2014, where I am integrated in CAP | Center for Applied Photonics.

As a Chemist, I have extensive background and experience in synthesis, characterization and (on a long list of) various laboratorial techniques, including the determination of photophysical properties. My experience began in a more biochemical-focused area with health-related studies, with animal supplementation applications for produce improvement, and later with methods for valorization of primary industry by-products.

Within the 7th FP of the EU (SNIFFER), I helped develop an intelligent network capable of detecting threats both in the food supply chain and in the prevention of (bio)terrorism. Sensors have been developed as well as ionic liquids with different properties, capable of being used as "bridges" to other sensors or sensitive structures, or to act as sensors themselves. Within the scope of CORAL, I developed sensors for the detection of chemical species in aqueous medium (NO3-, NO2- and PO4-), with the purpose of creating conditions for social and economic sustainability in marine exploitation. At this time, I'm a part of AGRINUPES project which aims to create sustainability conditions in agriuultural exploitations, namely through water and nutrient sustained usage; in order to attain this I research and develop sensors capable of determining their concentration "in situ", assuring their adequate fertilization, promoting ecological and finantial economy.

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Details

002
Publications

2019

Optical Sensing of Nitrogen, Phosphorus and Potassium: A Spectrophotometrical Approach Toward Smart Nutrient Deployment

Authors
Monteiro-Silva,; Jorge,; Martins,;

Publication
Chemosensors

Abstract
The feasibility of a compact, modular sensing system able to quantify the presence of nitrogen, phosphorus and potassium (NPK) in nutrient-containing fertilizer water was investigated. Direct UV-Vis spectroscopy combined with optical fibers were employed to design modular compact sensing systems able to record absorption spectra of nutrient solutions resulting from local producer samples. N, P, and K spectral interference was studied by mixtures of commercial fertilizer solutions to simulate real conditions in hydroponic productions. This study demonstrates that the use of bands for the quantification of nitrogen with linear or logarithmic regression models does not produce analytical grade calibrations. Furthermore, multivariate regression models, i.e., Partial Least Squares (PLS), which consider specimens interference, perform poorly for low absorbance nutrients. The high interference present in the spectra has proven to be solved by an innovative self-learning artificial intelligence algorithm that is able to find interference modes among a spectral database to produce consistent predictions. By correctly modeling the existing interferences, analytical grade quantification of N, P, and K has proven feasible. The results of this work open the possibility of real-time NPK monitoring in Micro-Irrigation Systems.

2018

Quantification of Ethanol Concentration in Gasoline Using Cuprous Oxide Coated Long Period Fiber Gratings

Authors
Monteiro Silva, F; Santos, JL; Marques Martins de Almeida, JMMM; Coelho, L;

Publication
IEEE Sensors Journal

Abstract

2017

The Antimicrobial Effect of Essential Oils Against Listeria monocytogenes in Sous vide Cook-Chill Beef During Storage

Authors
Gouveia, AR; Alves, M; de Almeida, JMMM; Monteiro Silva, F; Gonzalez Aguilar, G; Silva, JA; Saraiva, C;

Publication
Journal of Food Processing and Preservation

Abstract
Sous vide cook-chill (SVCC) is characterized by vacuum-packaging raw or partially prepared foods before pasteurization, followed by rapid chilling and storage below 3C. The application of essential oils (EOs) to food products is a suitable strategy to control pathogens and to extend their shelf life by reducing microbial levels and oxidative processes. The aim of this study was to evaluate the efficacy of Rosmarinus officinalis L. (rosemary) and Thymus vulgaris L. (thyme) EOs against Listeria monocytogenes ATCC 679, inoculated in beef processed by SVCC stored at 2 and 8C for 1, 2, 3, 7, 14, 21 and 28 days. The composition of EOs was identified by gas chromatography-mass spectrometry analysis. The main compounds identified in rosemary EO were eucalyptol (13.05%), camphor (8.93%), verbenone (8.58%), endo-borneol (7.87%) and a-pinene (6.78%) and in thyme EO were linalool (18.18%), thymol (7.48%), limonene (6.49%), endo-borneol (5.86%) and terpinen-4-ol (5.66%). Using the minimum inhibitory concentration (MIC) method, L. monocytogenes was inhibited at 3.9 µL/mL to thyme EO and at 62.5 µL/mL to rosemary EO. Beef samples of M. longissimus thoracis et lumborum were packaged in bags, inoculated and one of each EO was added at MIC values. Bags were vacuum-sealed and samples were processed at 55C/65 min for 3 log10 CFU/g reduction. A reduction of the counts of L. monocytogenes was observed in all samples at 2C. At 8C counts of L. monocytogenes were almost similar in control samples and those with thyme EO with an increase of the microbial counts since day 7. Inversely, counts of L. monocytogenes in beef samples with rosemary EO stored at 2 and 8C decreased about 2 log10 CFU. These results support the possibility of using rosemary EO as natural preservative due to its antimicrobial effect against L. monocytogenes. Also, our results confirm that an adequate chilling storage is essential to guarantee the safety of SVCC product regarding L. monocytogenes to avoid foodborne outbreaks. Practical Applications: Results support the possibility of addition of EO of rosemary as a natural preservative to reduce L. monocytogenes counts. Also, an adequate chilling storage for maintaining this pathogen at acceptable levels is of paramount importance in view of preventing food borne diseases. © 2016 Wiley Periodicals, Inc.

2016

Antimicrobial effect of essential oils of Laurus nobilis L. and Rosmarinus officinallis L. on shelf-life of minced "Maronesa" beef stored under different packaging conditions

Authors
Vilela, J; Martins, D; Monteiro Silva, F; Gonzalez Aguilar, G; de Almeida, JMMM; Saraiva, C;

Publication
FOOD PACKAGING AND SHELF LIFE

Abstract
The aim of this study was to evaluate the effect of essential oils (EOs) of plants naturally occurring in northern Portugal on the spoilage of fresh Maronesa beef burgers stored at 2 and 8 degrees C under different packaging conditions. EOs were obtained from dried leaves of laurel (Laurus Nobilis L.) and rosemary (Rosmarinus officinallis L.) by hydro-distillation using a Clevenger-type apparatus. Analysis of volatile composition of essential oils of rosemary and laurel was achieved by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Thermal Conductivity Detection (GC-TCD) resulting in the detection of 95.8% and 89.4% of its compounds, respectively. Fresh beef (semitendinosus and semimembranosus) of DOP-Maronesa breed (males; n = 4) were obtained from local market and transported to the laboratory. Samples were stored at 2 and 8 degrees C in two different conditions: aerobiosis (A) and vacuum (V) and analyzed at 0,1, 2, 3, 5, 7,10,14, 21 and 28 days for Lactic acid bacteria (LAB), Enterobacteriaceae, Pseudomonas spp., Fungi, Total mesophilic (TM) and psychrotrophic (TP), color (L*a*b*) and pH. Laurel was the most effective EO keeping pH from increasing. Coordinates L* and a* were higher on samples containing laurel EO for both A and V packaging. Laurel also showed better effect in reducing microbiologic counts in samples packed in A at both 2 and 8 degrees C and packed in V at 8 degrees C. Rosemary was effective in reducing microbial counts on all V samples stored at 2 degrees C. This study allows to conclude that Laurel EO has significant effect in shelf-life, maintaining fresh beef color.

2016

Involvement of endothelium in the vasorelaxant effects of 3,4-DHPEA-EA and 3,4-DHPEA-EDA, two major functional bioactives in olive oil

Authors
Segade, M; Bermejo, R; Silva, A; Paiva Martins, F; Gil Longo, J; Campos Toimil, M;

Publication
JOURNAL OF FUNCTIONAL FOODS

Abstract
The olive oil polyphenols 3,4-DHPEA-EA and 3,4-DHPEA-EDA displayed an endothelium dependent vasorelaxant effect in rat aorta, starting at similar to 1 mu M and abolished by N-G-nitro-L-arginine (L-NA) or N-acetylcysteine, and an endothelium-independent vasorelaxant effect, starting at similar to 10 mu M. Hydroxytyrosol only presented an endothelium-independent effect at 100 mu M. DHPEA-EA and 3,4-DHPEA-EDA, but not hydroxytyrosol, also increased NO generation within endothelial cells. At higher concentrations, the three compounds reduced argininevasopressin-induced increase of cytosolic Ca2+ concentration ([Ca2+](c)) in vascular myocytes. By UV-visible spectroscopy, we found that these polyphenols undergo autoxidative processes in organ-bath conditions. Thus, 3,4-DHPEA-EA and 3,4-DHPEA-EDA have an endothelium-dependent vasorelaxant effect caused by an enhanced NO production, probably through a redox mechanism within endothelial cells and an endothelium-independent vasorelaxant effect mediated by a reduction of agonist-induced [Ca2+](c) increase in vascular myocytes. Bearing in mind the plasmatic concentrations of these polyphenols following dietary intake of olive oil, these effects could modulate vascular tone in vivo.